1. Field of the Invention
The present invention relates to a camera which records data on film during a film feeding operation. More particularly, the present invention relates to a camera which corrects the film feed action in order that a single pulse generator may be used to determine a time for data recording and a time for stopping film feeding.
2. Description of the Related Art
Cameras are known which record the date of photography and similar data on film during a film feeding operation which occurs after a photograph has been taken. For example, a camera is disclosed in Japanese Laid-Open Patent Publication 63-27823 in which an array of light emitting elements (for example, LEDs) are driven to emit light simultaneously with the film feed action thereby causing data to be reproduced on the film as a succession of dot matrix characters. In these known types of cameras, pulse generators produce pulse trains which are used to detect a time when data may be recorded during feeding of the film, and the end of the action of feeding one frame of film. More specifically, in the known types of cameras two pulse generators are utilized: one pulse generator is used exclusively for detecting a time when data is to be recorded on the film during feeding of the film, and a second pulse generator is used exclusively for detecting the end of the action of feeding one frame of film.
A conventional type of pulse generator is illustrated in FIG. 1. The pulse generator includes a plurality of transmitting portions 12a and a plurality of non-transmitting portions 12b formed in adjacent sections on the inner periphery of a disk 10. A single non-transmitting portion 12c is formed on an outer periphery of the disk 10. The disk 10 is mounted on a free sprocket 14 of a film feeding system and is geared to rotate with the film feed action. A first photointerrupter 16 detects the non-transmitting portions 12b on the inner periphery of disk 10 and outputs a short period pulse train. A second photointerrupter 18 detects the single non-transmitting portion 12c on the outer periphery of disk 10 and outputs a long period pulse train. The short period pulse train is used to determine a time when data reproduction commences; the long period pulse train is used to determine when one frame of film has been fed. After the action of feeding the film by one frame has begun, when the number of pulses output by the first photointerrupter 16 reaches a predetermined number corresponding to the data reproduction commencement time, reproduction of the data takes place. Dot matrix characters are formed on the film by means of light generated by LEDs used for data reproduction. During data reproduction, the LEDs are driven on both the rising and falling edges of pulses generated by the photointerrupter 16 in order to produce characters of satisfactory precision. When the number of pulses output from the second photointerrupter 18 has reached a number corresponding to the feeding of one film frame, the operation of film feeding is stopped.
Pulse sequences of different periods have been used in conventional types of cameras because in a data reproduction system in which data reproduction is performed at each reversal of the pulse signals (i.e., at both the rising and falling edges of a pulse), dot matrix characters of satisfactory precision are formed when the pulse period is short. On the other hand, when using a pulse sequence to detect an amount of film feed corresponding to one frame, a short pulse period results in excess pulses being output because of overrun of the film due to the inertia of the film feed system. As a result, when the pulse number at this time is accumulated for each film feed, it becomes impossible to take the required number of photographs, and a longer pulse period becomes desireable.
However, two pulse generators require extra parts and excessive space for mounting. The parts and the labor required for mounting increase, and as a result, the camera is larger and the production cost of the camera increases.